Before conducting any laboratory activities, science teachers need to be in the know about the OSHA-required hierarchy of defense in the laboratory. At the top of OSHA's list are engineering controls, which are designed to reduce exposure to a chemical or physical hazard by using engineered machinery or equipment. This month's column outlines specific engineering controls required in academic laboratories. Although requirements will depend on individual states and which codes or standards they have adopted, the following are prudent safety practices that represent the professional safety standard recognized by the court in a legal situation.